This invention relates to a photosensitive member or a photoconductor for use in electrophotography.
It is advantageous that the surface of a photoconductor utilized in electrophotography is smooth as far as possible. The flatness of the surface of the photoconductor is important for the reasons that when a powder image formed by applying a charged toner consisting of a fine powder onto a latent image is transfer printed onto a copying paper or the like, blur of the reproduced picture image could be prevented or decreased as the smoothness of the photoconductor is improved and that cleaning of the toner remaining on the photoconductor after transfer printing becomes easy and perfect as the flatness is improved. Since the photoconductor or photosensitive layer is subjected to friction caused by cleaning means and by the copying paper, the surface hardness of the photoconductor should be high, and the surface of the photoconductor should be wear resistant, these characteristics being important for elongating the life of the photoconductor. Recently, cleaning of the photoconductor is generally made with a cleaning blade so that the smoothness of the photoconductor governs the cleaning effect, whereas the hardness is an important factor that determines the life.
The prior art photoconductor is constituted by an electroconductive substrate, usually a metal cylinder, and a layer of a photosensitive fine powder coated on the surface of the substrate by using a binder made of a synthetic resin which hardens when a solvent evaporates off. The surface of the photosensitive layer has an irregularity of the order of several tens of micron, so that when the remaining toner is cleaned by a blade, a certain quantity of the toner particles will remain in the recesses on the surface of the photosensitive layer. Such remaining particles would be heated and solidified by the friction between the particles and the cleaning blade thus forming larger particles having a tendency of forming scratches on the surface of the photoconductor or damaging the edge of the cleaning blade. Moreover, as the surface hardness of the photosensitive layer is relatively low, that is about 2H in terms of the hardness of pencils, the photosenstive layer would be readily worn out by the frictions between the photosensitive layer and the blade and between the photosensitive layer and the copying paper thus decreasing the life of the photoconductor.